1. Field of the Invention
The invention relates to a semiconductor memory device, and a method of refreshing the same, and more particularly, to a multi-channel semiconductor memory device, and a method of refreshing the same.
2. Description of Related Art
The demand by consumers and by industry for high-speed and highly integrated semiconductor memory devices continues to increase, and to meet this demand semiconductor memory devices are continuously being developed in various forms, such as multi-bank semiconductor memory devices and multi-chip semiconductor memory devices. Recently, multi-channel semiconductor memory devices have been proposed to enable high integration as well as to provide high bandwidth operation. A multi-channel semiconductor memory device has a plurality of sub-memory units (e.g., packaged integrated circuits, ICs) in a single chip. Each of the sub-memory units has input/output (I/O) pads and can operate as an individual memory device. Thus, each of the sub-memory units of the multi-channel semiconductor memory device operates as an independent memory device that inputs and outputs addresses, commands and data.